exaSound Audio Design has managed to carve out a conspicuous place in the high end audiophile DAC market since beginning business less than 4 years ago. Michael Lavorgna reviewed the e20 MK III DAC for AudioStream (see review) and found it to do a fine job on PCM and native DSD playback. The e22 DAC is exaSound’s recently introduced flagship 2 channel DAC having improved on the design of the e20 MKIII to provide a superior level of sound quality. exaSound also builds an e28 DAC that can deliver from 2 to 8 channels of PCM and DSD.

George Klissarov, President of exaSound Audio Design, has stated that the goal of his company is to deliver DACs that can play any studio master file in the way it was recorded using the most natural and simple methods without having to downsample or upsample.

E22 DAC Features

The e22 DAC is based on a single ES9018 Sabre32 reference DAC chip.

Asynchronous USB 2.0 that supports PCM resolutions to 384 kHz and DSD256 in both OSX Mavericks and Windows. The DAC also offers 2 SPDIF outputs for connection to CD players or DACs for PCM playback.

Data is provided from an FPGA core and is stored in the DAC FIFO memory buffer. The FPGA core makes sure that the buffer never becomes empty during playback. Data from the buffer is streamed to the DAC chip. The precision of the timing of the output stream is determined only by the DAC oscillators and is not degraded by the computer clocks or by delays caused by the USB interface.

Galvanic isolation between the USB computer output and the DAC circuits reduces noise created by ground loops and other computer generated noise transmitted by the USB cable.

A femtoclock capable of 0.082 ps (82fs) of DAC Master Clock jitter

Both gold plated XLR Balanced outputs and heavy duty RCA single end outputs that can be used simultaneously.

A high quality remote controlled volume control that functions in .5 dB steps that combines the best of digital and analog allowing one to connect the e22 directly to an amp. The volume control has a high SN Ratio with no loss of digital resolution. The e22 volume is controlled by the ES9018 DAC chip with the ESS Sabre chip actually performing the volume changes. It is independent from the Mac or Windows software volume control preserving the maximum possible signal to noise ratio. The volume control is bypassed at the 0 dB setting turning off any volume processing.

An external SMPS power supply with 11 power cleaning stages within the DAC. These multiple power cleaning stages allow every circuit to be powered separately with its own stage of power regulation. This feature prevents one power stage from modulating another stage helping to eliminate one source of DAC jitter.

A high quality headphone amplifier is provided with the e22 DAC.

12 VDC Trigger Output to control other devices.

Custom ASIO drivers for not only Windows, but OSX Mavericks that allows a higher level of performance in both operating systems. exaSound claims to be the first to offer ASIO support on OS X.

An Apple Remote Control is provided with the additional ability to re-program the DAC to work with most infrared remote controls using the Sony and NEC IR protocols.

Accepts a classic type B USB output cable connector

I asked George Klissarov to describe the upgrades found in the e22 DAC compared to the e20 MKIII:

The firmware was updated. The e22 DAC benefits from 1 year of additional work on fixes, optimizations, and improvements.

The analogue stage was improved to provide even lower noise and distortion.

The headphone amplifier now provides double the output voltage and can handle 2X higher output. This allows the e22 to drive a much wider range of headphones while maintaining very low noise and distortion levels.

The USB connector was updated as well as new heavy-duty RCA connectors.

The Master Clock was improved. The e20 master clock jitter level is rated at 0.13 ps. The e22 uses an upgraded femtoclock resulting in 0.082ps (82fs) of jitter. exaSound did trials with the femtoclock on the e20, but the new technology was fully implemented on the e22 DAC.

12 V Trigger was included on the e22. The e22 can power-on / power-off power amplifiers or other devices equipped with a 12V Trigger input.

The Front Panel
The e22 DAC’s controls are nicely laid out and quite intuitive to use. Power, Volume, Input, and Setup for programming another remote are provided. The display shows the input, volume level, number of channels, and file type (PCM or DSD) with sample rate.

Associated Components
An early 2011 MacBook Pro 2.3 GHz, 16 GB RAM with Samsung SSD was used with a Promise Pegasus and GRAID Thunderbolt drives for the music libraries. I had very good results using the JCAT USB cable with the e22 and my reference USB cable, the Synergistic Research Galileo LE. I was able to evaluate the e22 running OSX Mavericks and Windows 8.1 Pro 64 in Boot Camp. I listened to the e22 placed directly on my equipment rack, but I did find that the e22 benefited from after-market isolation feet. I successfully used the Symposium Acoustics Rollerblocks with Grade 3 Superballs placed on a Synergistic Research Tranquility Base.

OSX software included Decibel, J. River Media 19, and Audirvana Plus. I used J. River Media 19 for Windows.

First Sonic Impressions
The first sound characteristic of the e22 that grabbed my attention was the enormous soundstage that this DAC is capable of rendering. Soundstage width was about as large as I have experienced with any DAC, while the depth of the reproduced stage was very impressive. If one views a DAC’s potential sound on a continuum of dark to light, I would place the e22 as a light sounding DAC. The e22 struck me as being very neutral sounding without excessive midrange warmth or other colorations. Resolution, focus and definition from top to bottom were excellent. Most users will find this to be a very revealing DAC that can dig down to expose the smallest details of the music. Now some of you might think that this level of detail comes at a price; hardness and a lack of warmth. But nothing could be further from the truth concerning the sound of the e22 DAC. This is a DAC that one can listen to for hours on end without digital fatigue. I also felt that the dynamic qualities of the e22 DAC were very good as well. Both macro and micro dynamic changes could be perceived with this DAC in a very natural and pleasing manner. The e22 was also a champ at the way it handled DSD recordings. While the midrange ease of DSD is reproduced, the high end detail is some of the best I have ever heard from any DAC playing DSD files. But this leads us to a discussion of the impressive DSD performance that comes with the ASIO drivers provided for OSX Mavericks and Windows.

OSX Mavericks and the exaSound ASIO Driver
To play the exaSound e22 DAC with OSX, one must load the drivers provided by exaSound. Two drivers are installed; a Core Audio driver and an ASIO driver. Also installed is a small program that places the Dashboard icon on the OSX menu bar located at the upper right hand portion of the screen. This Dashboard program allows one to select the Core Audio or ASIO output for the exaSound e22. If you are running OSX Mavericks, you will be able to play DSD256 (4X DSD) files. Both drivers support Exclusive Access and Integer mode playback.

A good question at this point is why the need for an ASIO driver for OSX? exaSound has pointed out that playing DSD files under the DoP (DSD over PCM), results in a 30 to 50 percent increase in CPU processing overhead. Also, the DoP implementation for DSD256 requires support for PCM at 705.6 kHz and 768 kHz. These high sampling rates pose a significant challenge for both the computer CPU and USB audio interface.

I have had no previous issues playing DSD files with DoP for a number of different DACs. I thought the sound was quite good with DoP, but I have heard comments suggesting otherwise. One of my designer friends feels that DoP sucks the life out of the music.

To play files with the ASIO driver you will need to use a software program that supports ASIO for OSX. At this point in time I know of only one program; the excellent minimalist program Decibel supports ASIO for OSX. One can compare playing PCM and DSD files with the standard Core Audio driver and the same files played with the ASIO driver. The ASIO driver bypasses Core Audio with a more direct path for processing than the standard Core Audio driver.

Now some will ask does any of this have any significance for DSD 64 files; the most common type of DSD file available? DSD128 titles are rare, and DSD256 at this point beyond rare. The answer to this question is an overwhelming yes!

I sat back and listened to a large number of DSD64 files under both ASIO and Core Audio with Decibel. The ASIO driver sounded much better than the Core Audio driver that used DoP; and not by a small amount. The DoP playback with the Core Audio driver sounded somewhat compressed with less bloom and high end air. The soundstage was far more open sounding listening with the ASIO driver. And it wasn’t just DSD that benefited from the ASIO driver playback, but also PCM files. The PCM files simply sounded better with the ASIO exaSound driver.

I was able to play several DSD256 sample files available from Native DSD Music. They did sound extremely good using Decibel and the ASIO driver. But I encountered no problems using the Core Audio driver and DoP other than the sonic differences previously noted.

Windows ASIO Driver
I loaded the Windows ASIO driver into Windows 8.1 Pro 64. Unlike other Windows drivers I have installed, the exaSound does not appear in the Control Panel Music devices. The exaSound ASIO driver was seen in the selectable devices in J. River Media. The ASIO driver played DSD files directly without needing DoP. The Windows driver / J. River had the same huge soundstage that I heard with the OSX ASIO setup using Decibel and similar sonic qualities emerged. In fact, I was very surprised how much closer Windows 8.1 Pro 64 / J.River sounded when compared to OSX Mavericks / Decibel using the ASIO driver.

George Klissarov’s Comments on exaSound's ASIO Drivers for OSX and Windows
I was so impressed with the sonic performance of the exaSound ASIO drivers for both OSX and Windows, that I asked George if he could provide our readers greater insight on this interesting topic.

Computer sound systems are made and optimized for two purposes:

To be user friendly.

To be compatible with everything and everybody, to support a wide range of audio applications and hardware, from Skype to portable players and games.

The need for convenience and versatility and the ever increasing demand for new feature cause great complexity. Sound quality is a secondary concern and it is often compromised.

Basically the sound system and the drivers have to deliver performance in several ways:

The sound stream data have to be delivered from the player software to the DAC chip without errors or unwanted changes. This is called bit-perfect operation.

The precision of playback timing is of huge importance. Each data sample must appear on the input of the DAC chip at the right time, no sooner and no later. Computer clocks can run at the wrong speed and also can be jittery. The best solution to the inconsistent computer timing is the use of asynchronous protocol for exchange of data between the computer and the DAC. Asynchronous means that the DAC can ask the computer for more data when it is needed, instead of being told by the computer the timing of the data beat. Asynchronous operation makes the DAC the master device. Since the cheapest DAC has a better master clock than the most expensive personal computer, it makes sense to put the DAC in charge of the playback timing.

Cutting edge high resolution recordings require support for high DSD and PCM sampling rates. These high rates can test the limits of CPU and USB performance and require driver and sound system efficiency.

Issues with the Windows Sound System

It is well known that on Windows, the built-in volume control, mixer and sampling rate converter are not what we call "audiophile-grade". They can be bypassed, but the user is exposed to the complexity of driver setup and the end result is unstable because Windows updates or third-party software can reconfigure the sound-streaming chain.

In addition Windows drivers usually are unable to switch sampling rates to match the format of the current track. Users have to reconfigure the driver for every PCM format if they want to achieve bit-perfect playback.

Windows has no built-in native support for DSD.

There are performance issues with the extreme PCM sampling rates of 352.8 and 384 kHz.

Core Audio Limitations
The Core Audio sound system used on Mac OS X is much better compared to the Windows sound system, but it has the same limitations when it comes to DSD. Both Windows and Mac need a workaround like DSD over PCM (DoP) for DSD support.

DoP creates a significant performance overhead. A DoP marker byte is required for every two bytes of data. This causes 33% overhead for 24bit drivers. For 32bit drivers like ours the overhead can be 50%.

It is quite difficult to implement support for DSD256 using the DoP standard. The DoP implementation of DSD 256 requires support for PCM at 705.6kHz and 768kHz. Such sampling rates are a real challenge for both computer CPUs and USB audio interfaces.

Using the Core Audio system with DoP256 is challenging. The CPU performance requirements for processing 768 kHz sampling rate for DSD256, the 30% to 50% bandwidth overhead of the DoP format, and the need to support 8 channels for some of our DACs test the performance limits of the current software and hardware.

Another issue with Core Audio is the inconsistent support for integer mode. All DAC chips use integer data and integer mode is a way to achieve bit-perfect streaming. Unfortunately integer mode is not available on OS X Lion and Mountain Lion. It was reintroduced on OS X Mavericks, but it didn't work with all drivers. There are two Core Audio driver architectures - Kernel Space and User Space. Most older drivers are Kernel Space and integer mode on Mavericks works only for User Space drivers.

There is another architectural limitation of the Core Audio sound system. With Core Audio the Mac is always the master device, and the DAC is the slave device. The playback timing accuracy is influenced by the computer timing. In my opinion asynchronous USB Audio Class 2.0 implementations with Core Audio are inferior compared to ASIO.

ASIO Benefits
ASIO solves all these issues. ASIO is an audio steaming protocol used in recording studio environments.

Unlike the computer sound systems ASIO is designed for one purpose - sound fidelity.

All these factors contribute to the superior sonic fidelity experienced with the exaSound ASIO drivers.

The topic of ASIO vs. built-in Windows and Mac sound systems brings a broader question. Computer hardware is not created to be used as audiophile-grade gear. There are more than the drivers to achieve high-fidelity sound with computers. There are two alternative approaches:

To use audiophile-grade computer power supplies, special USB cards and fine USB cables. In addition, to customize the operating systems by removing unnecessary processing in order to improve the computer timing. All these improvements make computers better devices for audio playback, but they address the symptoms, not the root causes of the problems.

To address the issues and limitations of computer hardware and operating systems outside the computer - in the DAC.

Here at exaSound we like the second approach. We try to design our hardware, firmware and drivers to solve the issues of computer playback. Basically there are four devices inside the e22 box, a DAC, a reference quality master clock, a USB noise filter and a power conditioner. Our devices are quite insensitive to the quality of the attached computer and the USB cable.

Musical Impressions
As I listened to many titles across different formats, I was struck at just how revealing the e22 was of low level detail. This DAC lets you hear tonal nuances, spatial resolution, and transient quickness against a very black sonic background.

Blue Coast Records Quiles & Cloud Seminole Star (dsf) DSD64 is an excellent example of the level of sonic detail that the e22 can reproduce. This title was recorded to 2 inch analog tape and mixed in DSD and mastered to DSD. The acoustic instruments sounded very real with immediacy and a delicacy in tone and texture. The e22 never lost resolution when multiple instruments and voices were reproduced. Again, I am not accustomed to this level of high end resolution in the playing of DSD titles.

Classical music titles were equally impressive played in the DSD format. Downloaded from the Pentatone site was the wonderful DSD64 recording of Sa Chen’s performance of the Grieg and Rachmaninov piano concertos. I have always felt that this recording was a little warm and not particularly focused, but I was wrong. Listening to Sa Chen’s performance with the exaSound e22 DAC was a totally new experience. While the sound was harmonically rich, I heard reproduction of instrumental textures with air and bloom around the instruments that I had not heard with other DACs reproducing this DSD64 recording. The soundstage was extremely wide and deep with a wonderful sense of realism.

The Channel Classics recording of the Magdalena Consort’s Recreation for the Soul DSD64 was equally stunning played through the e22 in Windows or OSX with the ASIO drivers. The e22 successfully captured every vocal inflection and nuance of this Bach sacred choral music. The chamber orchestra emerged from a richly layered soundstage without a hint of noise or digital artifacts. As with the Sa Chen recording, the natural midrange qualities were quite obvious but with outstanding high end resolution.

I just had to mention one more DSD recording; Eric Bibb’s A Selection of Analogue found at Opus 3 for download. This DSD128 recording was made from the original master analog tapes. I think the sound quality of this recording of blues and folk style music is top drawer. The relaxed presentation comes across with realism and liquidity of the real thing. This title is highly recommended.

Moving to PCM, I found that the quality of reproduced sound was similar to what I had heard with DSD, but with PCM’s ability to squeeze out more high end resolution from excellent recordings. Patricia Barber’s Smash 24/192 sounded terrific played through the exaSound e22. There was excellent transient quickness and impact with a wonderful vocal transparency to Patricia’s voice. The exaSound did not add extra warmth or low to midrange coloration, but was very revealing and natural sounding.

The acoustic space of the Buena Vista Social Club 24/96 was quite startling heard through the exaSound e22 DAC. I could easily pick out front to back placement of the instruments with a natural reproduction of the voices and instruments recorded in its acoustic space. I have often heard a bit of midrange heaviness in this recording, but the exaSound did not exhibit this quality. This was one of the most enjoyable listening sessions of this well-known recording I have yet experienced.

I have several DXD titles 24/352.8 that were begging to be played on the exaSound e22 DAC. The Hoff Ensemble Quiet Winter Nights sounded very relaxed, natural, with good body and weight to the bass. The vocalists had a tonal naturalness of the real thing with resolution and transparency that was world class. The exaSound had no issues playing different formats or resolutions and was hiccup-free in its performance.

The Volume Control
I did evaluate a direct connection of the e22 DAC with the balanced inputs of my Ayre MX-R amps. The sound was quite good with the internal volume control of the e22. I still preferred the sonic results using the Ayre KX-R preamp, but the exaSound volume control will no doubt satisfy many users.

Comparisons with the my Favorite Bits DACs
All of my favorite DACs (see Favorite Bit DACs) that I have reviewed for AudioStream cost far more than the exaSound e22 DAC. But in some ways, it deserves to be compared to these stellar performers. Compared to these DACs, the exaSound does not have the midrange richness or sonic weight of my top picks. Also, the bass does not have the power or slam that these other DACs have. But the exaSound holds its own in soundstage, detail resolution, and has some pretty amazing DSD performance.

An Exceptional Performing DAC
George Klissarov and his design team at exaSound deserve some major accolades for the creation of the e22 DAC and associated software. exaSound has looked at the total picture of integration of computer and DAC to obtain performance that many other DAC manufacturers will envy. exaSound's unique approach to computer optimization has resulted in a DAC that offers not only excellent PCM playback, but some of the best DSD sound I have yet experienced.

Since Vista, Windows has used an audio-management scheme they call WASAPI. I'm not sure I understand how ASIO fits into this, except that WASAPI has an 'exclusive' mode that allows the software program to address the audio hardware directly, but requires special drivers (ASIO?) to control the conversions to or from analog.

Could you shed some more light on how ASIO drivers fit into this scheme? Thanks.

Informative review, thanks! The size of this DAC makes me think of it as a desktop component, especially with the headphone out. Did you try it with headphones? At the same price as the VEGA, I wonder how these compare.

My DAC supports 705khz and 768khz, and plays back DSD256 encoded files via DoP with no problems whatsoever. I don't have a 'monster' of a PC, either, it is typical. I have never experienced an issue with these sample rates. In my opinion, the difficulty factor is overstated here.

Also, I hear no difference whatsoever in playback quality when switching between DoP and ASIO Native DSD streaming. I submit that any differences heard by the reviewer lie in the driver itself, and cannot be attributed to simply DoP vs ASIO.

Finally, of course the Exasound uses the ESS chipset, which is not a native DSD chipset. Now, I am sure it sounds just fine playing back DSD, but it is anything but native DSD. The signal path for DSD in the ESS chip goes something like this... (as best we can ascertain, what really happens in these 'black boxes', well...)

1 bit DSD is filtered via a 3 pole IIR filter at a selectable 50, 60, or 70khz cutoff. The output of said filter is no longer bitstream. Pulse Density amplitude values are now no longer pulse density. Amplitude values are now encoded in multi-bit samples, likely at the same sample rate as what went in. Any volume control is applied here, now that we have multi-bit samples to work with. The nature of the volume control is unknown, but it is 32 bit, and possibly involves a noise-shaping stage. The the result of all this goes to an Asynchronous Sample Rate Converter. (which cannot be bypassed. In a 'synchronous' implementation, the ASRC is still active; it is just now allegedly a 1:1 system. Also note, you CAN'T use an ASRC on DSD data. You CAN use it on high sample rate, noise-shaped, um.. PCM data) After the ASRC, the data then goes to the proprietary Delta Sigma modulator.

Whew!!!! And the result of all of this is supposed to be 'native DSD?"

Or take Exhibit B...

DSD bitstream is low pass filtered in a single analog conversion step.

Sorry, but I will take the latter any day of the week. In this case, less definitely is more. Less DSP, the better.

Granted, I am sure the Exasound sound great on DSD. I also believe there are others that sound better.

mlgrado, you are extremely confused regarding the difference between PCM and multi-bit PDM. Converting 1-bit PDM (DSD) to multi-bit PDM is a lossless process. You can then do DSP on multi-bit PDM, such as volume control. Going back to 1-bit DSD would not be lossless, but a DAC that's natively multi-bit PDM like the ESS would not be doing so, it would then be going directly to analog. Don't take my word for it, see this response from the founder of Mytek:

"Also, I hear no difference whatsoever in playback quality when switching between DoP and ASIO Native DSD streaming. I submit that any differences heard by the reviewer lie in the driver itself, and cannot be attributed to simply DoP vs ASIO."

Yes, one can only conclude that ASIO sounded best for the e22. But there is a technical basis for this conclusion.